CN102331462B - Method for measuring ammonia content in water-based adhesive for cigarettes - Google Patents

Abstract

The invention discloses a method for measuring ammonia content in water-based glue for tobacco. Tobacco water-based rubber samples were extracted with hydrochloric acid aqueous solution, and the extract was centrifuged, filtered, and then analyzed by ion chromatography. At the same time, different concentrations of NH ⁴ standard working solutions were prepared and analyzed by ion chromatography. Quantitative analysis was carried out by the external standard method, and the regression analysis was carried out with the chromatographic peak area of ammonia and its corresponding concentration to obtain a standard curve, the correlation coefficient was greater than or equal to 0.999, and the prepared samples were measured to measure the peak area of ammonia in the sample. The standard curve is used to obtain the content of ammonia in the sample, which is qualitatively determined by the retention time of the standard substance and quantified by the peak area. The invention can effectively detect the content of ammonia in the tobacco water-based glue, and the operation is fast, simple and easy. The gradient elution is used to eliminate the interference of various ions, especially sodium ions, and solve the rapid determination of the ammonia content in the tobacco water-based glue. It fills up the gap in the current determination of tobacco water-based gum ammonia.

Description

A method for measuring ammonia content in water-based glue for tobacco

technical field

The invention belongs to the technical field of cigarette processing, and relates to a physical and chemical inspection technology for tobacco water-based glue, in particular to a method for measuring ammonia content in tobacco water-based glue.

Background technique

Tobacco water-based adhesive is an indispensable material in the cigarette production process. At present, most of the adhesives used in domestic cigarette production are chemically synthesized water-based adhesives. According to the relevant testing standards for tobacco water-based adhesives, pH measurement is an important task. An important indicator, in order to make the pH value of the tobacco water-based adhesive meet the corresponding technical standards, some merchants will pass ammonia gas to adjust the pH value, so the residual ammonia in the product will not only bring unpleasant pungent smell, but also seriously Affect the sensory quality of cigarette products. Because in the process of smoking cigarettes, excessive ammonia will produce a strong irritant, causing the smoker's throat to constrict, feel coughing, and the tip of the nose and tongue are unbearably spicy. The formation of flavor energy. Therefore, the analysis and monitoring of ammonia residues in water-based adhesives for tobacco use is of great significance both in terms of cigarette smoking safety and sensory quality.

C.H.Sloan et al. used the ammonia electrode method to measure ammonia in cigarette smoke. This method is complicated in pretreatment. Use dilute hydrochloric acid solution to absorb the ammonia in the flue gas, then add sodium hydroxide solution, distill, and then use dilute hydrochloric acid solution to absorb the overflowing ammonia. , and then add sodium hydroxide solution to measure, the operation is complex, and it is easily affected by the environment. C.W.Ayers et al. used gas chromatography to measure ammonia in cigarette smoke. In this method, the sample solution needs to be dried with alkali before gas chromatographic analysis, and the peak of the sample appears tailing phenomenon. To overcome this, an additional A very complex by-pass device was developed. The method is tedious in operation, complicated in sample injection, and narrow in linear range. Domestic research on this aspect started late, and currently it is mainly related to the determination of ammonia content in mainstream smoke of cigarettes. There is no report on the determination method of ammonia in water-based rubber for tobacco.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the prior art, to provide a method for measuring the ammonia content in the tobacco water-based glue, and to directly measure the tobacco water-based glue by ion chromatography conductivity detection (IC), which significantly improves the measurement efficiency and accuracy Spend.

The purpose of the present invention is achieved through the following technical solutions.

Unless otherwise stated, the percentages used in the present invention are all percentages by weight.

A method for measuring ammonia content in water-based glue for tobacco use, comprising the following steps:

1. Weigh 0.3 g of the water-based adhesive sample to be tested and place it in a 50 mL conical flask;

2. Pipette 20 mL of hydrochloric acid solution with a concentration of 10 mmoL/L, add it to the Erlenmeyer flask containing the sample to be tested, plug the stopper, shake at 150 r/min for 10 min, and stand still;

3. Take 10 mL of the extract from step (2) and put it in a centrifuge tube, centrifuge at 6500 r/min for 20 min, take the supernatant and pass it through a 0.2 μm water phase filter membrane, and analyze it with an ion chromatograph;

4. Prepare the NH ⁴ standard working solution: weigh the ammonia standard solution, dilute it with 10 mmoL/L hydrochloric acid aqueous solution, and then gradually dilute it with a 10 mmoL/L hydrochloric acid aqueous solution to obtain a NH ⁴ standard working solution with a concentration gradient;

5. Analyze the prepared ^NH4 standard working solutions with different concentrations by ion chromatography, perform quantitative analysis with the external standard method, and perform regression analysis with the chromatographic peak area of ammonia and its corresponding concentration to obtain a standard curve, and the correlation coefficient is greater than or equal to 0.999, the prepared sample is measured, the peak area of ammonia in the sample is measured, and brought into the standard curve to obtain the content of ammonia in the sample;

6. Qualitative by retention time of NH ⁴ standard substance, quantitative by peak area.

Wherein, the analysis conditions of the ion chromatograph are: adopt CS-12A cation exchange column, CG-12A guard column, CSRS-ULTRA-II (4mm) self-regenerating cation suppressor; eluent flow rate: 1.2 mL/min, The eluent is prepared from deionized water and methanesulfonic acid solution with a concentration of 0.05 moL/L, and is eluted with a gradient eluent; column temperature: 30°C; detection cell temperature: 35°C; injection volume: 25 μL; Current: 90 mA; the gradient elution process is: 30% methanesulfonic acid solution and 70% methanesulfonic acid solution balance for 6 min, and the eluent composition is 50% deionized water and 50% methanesulfonic acid The acid solution runs for 6.1-14.5 minutes, and the eluent becomes 30% methanesulfonic acid solution and 70% methanesulfonic acid solution for 14.5-18 minutes.

The specific preparation method of the ammonia standard working solution with a concentration gradient described in step 4 is: pipette 1 mL NH ₄ ⁺ standard solution, use 10 mmoL/L hydrochloric acid aqueous solution to make up the volume in a 100 mL volumetric flask, and obtain a concentration of 10 μg/mL NH ₄ ⁺ primary standard solution, take 0.5 mL, 1.0 mL, 3.0 mL, 5.0 mL, 10 mL, 15 mL, 20 mL primary standard solution respectively, and dilute to 100 mL with 10 mmoL/L hydrochloric acid aqueous solution mL volumetric flasks, obtain a standard sequence at the following concentrations: 0.05 μg/mL, 0.1 μg/mL, 0.3 μg/mL, 0.5 μg/mL, 1.0 μg/mL, 1.5 μg/mL, 2.0 μg/mL.

Compared with the prior art, the present invention has the following advantages:

1. The present invention uses ion chromatography conductometric detection (IC) for the first time to accurately measure the ammonia content in the water-based glue for cigarettes. The operation is fast, reliable, simple and easy, and has the advantages of accurate measurement results, high sensitivity and good repeatability The invention has the advantages of filling up the gaps in the prior art.

2. Using hydrochloric acid aqueous solution with a concentration of 10 mmoL/L as the extraction agent can effectively improve the purification effect and recovery rate, and can effectively extract ammonia from water-based glue, because ammonia is alkaline and easily reacts with acid solution was extracted.

3. In order to have a better separation degree, the present invention adopts gradient elution, which can separate the component peaks of the main interfering substance sodium ions and ammonia ions without mutual interference, and meet the quantitative requirements.

4. Detection limit and quantitative limit of the inventive method

The standard solution with the lowest concentration was measured in parallel 10 times, and its standard deviation was calculated. 3 times the standard deviation was used as the detection limit of the method, and 10 times the standard deviation was used as the limit of quantification. The results were detection limit: 0.007 μg/g, quantification limit: 0.024 μg/g.

5. Repeatability and standard addition recovery test of the inventive method

We did blank spike and sample spike respectively, and then carried out sample pretreatment and ion chromatography analysis respectively, and calculated the recovery rate according to the spiked amount and the measured value. The results are shown in Table 1. It can be seen from Table 1 that the average recovery of diethylene glycol was 97.89% at the three spiked levels. The average relative standard deviation (RSD) was 3.14%, indicating that the recovery rate of this method is high and the repeatability is good.

Table 1 Ammonia recovery and repeatability test (n=5)

6. Repeatability test of pretreatment of ammonia in the present invention

The same sample was sampled at different times, and the relative standard deviation of the measured value was calculated through the above-mentioned sample pretreatment and ion chromatography conductivity detection. The results are shown in Table 2, which shows that the pretreatment of the method has good repeatability. the

Table 2 Repeatability of determination of ammonia content in water-based adhesive for tobacco

Description of drawings

Fig. 1 is the flowchart of assay method of the present invention;

Fig. 2 is the chromatogram of ammonia standard working solution;

Fig. 3 is the standard curve figure of ammonia;

Fig. 4 is a chromatogram of ammonia in a sample of water-based adhesive for tobacco use.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and examples, but the accompanying drawings and examples do not limit the present invention.

Example 1

Determination of ammonia content in tobacco water-based adhesive (determination process shown in Figure 1)

(1) Preparation of extract: Accurately weigh 1.0 g of 36%-38% HCl solution, dilute to 1L with 18.2Ω deionized water, and obtain 10 mmoL/L hydrochloric acid aqueous solution.

(2) Preparation of the standard working solution: the ammonia standard solution was purchased from the National Material Center, the concentration is: 1000 μg/mL, the specific preparation method of the ammonia standard working solution with a concentration gradient is: pipette 1 mL NH ₄ ⁺ standard solution , dilute to 100 mL volumetric flask with 10 mmoL/L hydrochloric acid aqueous solution to obtain NH ₄ ⁺ primary standard solution with a concentration of 10 μg/mL, take 0.5 mL, 1.0 mL, 3.0 mL, 5.0 mL, 10 mL, 15 mL, 20 mL primary standard solution, dilute to 100 mL volumetric flask with 10 mmoL/L hydrochloric acid aqueous solution, and obtain standard series with the following concentrations: 0.05 μg/mL, 0.1 μg/mL, 0.3 μg/mL, 0.5 μg /mL, 1.0 μg/mL, 1.5 μg/mL, 2.0 μg/mL. The obtained standard working solution is prepared and used now; the chromatogram of the ammonia standard working solution is shown in Figure 2.

(3) Preparation of sample solution: Accurately weigh 0.3 g of tobacco water-based adhesive sample, put it into a 50 mL conical flask, accurately add 20 mL of 10 mmoL/L hydrochloric acid aqueous solution with a pipette, and shake at 150 r/min for 10 min , pipette 10 mL into a centrifuge tube, centrifuge at 6500 r/min for 20 min, take the supernatant and pass it through a 0.2 μm water phase filter membrane, and analyze it with an ion chromatograph.

(4) Ion chromatograph analysis: Take standard working solution and sample solution for ion chromatograph analysis respectively, and the chromatographic analysis conditions are: CS-12A cation exchange column, CG-12A guard column, CSRS-ULTRA-Ⅱ (4mm) Self-regenerating cation suppressor; eluent flow rate: 1.2 mL/min, eluent is composed of deionized water and methanesulfonic acid with a concentration of 0.05 moL/L, and is eluted with gradient eluent; column temperature: 30°C; detection pool Temperature: 35°C; Injection volume: 25 μL; Current: 90 mA; The gradient elution process is: 30% methanesulfonic acid solution and 70% methanesulfonic acid solution are equilibrated for 6 minutes, and then the eluent is composed of Run for 50% deionized water and 50% methanesulfonic acid solution for 6.1 to 14.5 minutes, and change the eluent to 30% methanesulfonic acid solution and 70% methanesulfonic acid solution for 14.5 to 18 minutes;

(5) Standard curve drawing and result calculation: firstly, regression analysis was performed based on the peak area of the ammonia component peak corresponding to its corresponding concentration, and the standard curve (as shown in Figure 3) and regression equation and correlation coefficient were obtained, and the lowest concentration of the working solution was taken. Do 10 parallel experiments, calculate the standard deviation, 3 times of the standard deviation is the detection limit, and 10 times of the standard deviation is the quantitative detection limit, the results are as shown in Table 3;

Table 3 Standard curve and detection limit of ammonia in tobacco water-based adhesive

Name retention time (min) regression equation correlation coefficient Detection limit (μg/g) Limit of quantitation (μg/g) ammonia 4.83 y=6.7625x+0.0022 0.9998 0.007 0.024

Then the chromatographic peak area that records ammonia in the sample is brought into the standard curve drawn, obtains the content of ammonia in the sample, and calculation formula is as follows:

X=(C×V×17)/(m×18)

In the formula: X- content of ammonia in the sample, the unit is microgram/gram (μg/g);

C- The content of ammonia in the sample read from the standard working curve, in micrograms/gram (μg/g);

V- The volume of the extract added to the sample, in milliliters (mL);

The formula weight of 17- _NH3 ;

The formula weight of 18-NH ⁴⁺ ;

m- the mass of the pattern, in grams (g);

The specific results are shown in Table 4.

Table 4 Test results of ammonia content in water-based adhesive for tobacco

compound Content (μg/g) ammonia 78.85

Example 2

  Determination of ammonia content in different brands of tobacco water-based adhesives:

1. Preparation of sample solution: Accurately weigh 0.3 g of each of the 6 brands of tobacco water-based adhesive samples, put them into a 50 mL conical flask, and accurately add 20 mL of 10 mmoL/L hydrochloric acid aqueous solution with a pipette, 150 r/L min Shake for 10 min, pipette 10 mL into a centrifuge tube, centrifuge at 6500 r/min for 20 min, take the supernatant to pass through a 0.2 μm water phase filter membrane, and analyze it on an ion chromatograph; the chromatogram of ammonia in the sample is shown in Figure 4 Show.

2. Using the chromatographic conditions of Example 1 to analyze the sample solution; the chromatogram of ammonia in the sample is shown in Figure 4.

3, the chromatographic peak area that records ammonia is brought into the standard equation of embodiment 1, obtains the content of ammonia in the sample, calculation method is with the calculation method of embodiment 1, and concrete result is as shown in table 5:

Table 5 Test results of ammonia content in water-based adhesive for tobacco

Note: N.D. means not detected

Example 3

The present embodiment verifies the repeatability and standard addition recovery of the inventive method:

Add different concentrations of standard working solutions to the samples respectively, measure each sample 3 times, measure the chromatographic analysis conditions with the same embodiment 1, and calculate the recovery rate of ammonia in the water-based glue for tobacco and the concentration after the addition of the standard according to the analysis results. The relative standard deviation of determination, the result is as shown in table 6:

Table 6 Standard addition recovery and relative standard deviation results

It can be seen from Table 6 that the recovery rate of ammonia is between 94% and 101%, and the average relative standard deviation (RSD) is between 2.0 and 5.0, which shows that the recovery rate of the method of the present invention is high and the repeatability is good.

Claims (2)

1. A method for measuring ammonia content in the water-based adhesive for tobacco, comprising the following steps: (1) Weigh 0.3 g of the water-based adhesive sample to be tested and place it in a 50 mL conical flask; (2) Pipette 20 mL of hydrochloric acid solution with a concentration of 10 mmoL/L, add it to the Erlenmeyer flask containing the sample to be tested, plug the stopper, vibrate at 150 r/min for 10 min, and stand still; (3) Take 10 mL of the extract from step (2) and put it in a centrifuge tube, centrifuge at 6500 r/min for 20 min, take the supernatant and pass it through a 0.2 μm water phase filter membrane, and analyze it on an ion chromatograph; The analysis conditions are: CS-12A cation exchange column, CG-12A guard column, CSRS-ULTRA-II self-regenerating cation suppressor; eluent flow rate: 1.2 mL/min, eluent made of deionized water and concentration of 0.05 Prepared with moL/L methanesulfonic acid solution, eluted with gradient eluent; column temperature: 30°C; detection cell temperature: 35°C; sample volume: 25μL; current: 90 mA; the gradient elution process described It is: 30% methanesulfonic acid solution and 70% methanesulfonic acid solution equilibrate for 6 minutes, the eluent composition is 50% deionized water and 50% methanesulfonic acid solution, run for 6.1-14.5 minutes, the eluent becomes Run for 14.5-18 minutes for 30% methanesulfonic acid solution and 70% methanesulfonic acid solution; (4) Prepare the ammonia standard working solution: weigh the ammonia standard solution, dilute it with 10 mmoL/L hydrochloric acid aqueous solution, and then gradually dilute it with 10 mmoL/L hydrochloric acid aqueous solution to obtain the ammonia standard working solution with a concentration gradient; (5) Analyze the prepared ammonia standard working solutions with different concentrations by ion chromatography, conduct quantitative analysis with external standard method, and perform regression analysis on the chromatographic peak area of ammonia and its corresponding concentration to obtain a standard curve, and the correlation coefficient is greater than or equal to 0.999, the prepared sample is measured, the peak area of ammonia in the sample is measured, and brought into the standard curve to obtain the content of ammonia in the sample; (6) Qualitative by retention time of ammonia standard substance, quantitative by peak area. 2. The assay method according to claim 1, characterized in that: the specific preparation method of the ammonia standard working solution with a concentration gradient described in step (4) is: pipette 1 mL of ammonia standard solution, and use 10 mmoL/ Dilute 1 L hydrochloric acid aqueous solution to a 100 mL volumetric flask to obtain a primary standard solution of ammonia with a concentration of 10 μg/mL, and take 0.5 mL, 1.0 mL, 3.0 mL, 5.0 mL, 10 mL, 15 mL, and 20 mL of the primary standard solution respectively. Standard solution, dilute to 100 mL volumetric flask with 10 mmoL/L hydrochloric acid aqueous solution, and obtain the standard sequence of the following concentrations: 0.05 μg/mL, 0.1 μg/mL, 0.3 μg/mL, 0.5 μg/mL, 1.0 μg/mL , 1.5 μg/mL, 2.0 μg/mL.

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